1. Statement of the Technical Field
The present invention relates to asynchronous communications and more particularly to messaging systems.
2. Description of the Related Art
Distributed applications have begun to proliferate, as have a host of previously unexplored problems associated with message synchronization, transmission reliability, system scalability, and message security. Present solutions include conventional messaging systems formed from loosely coupled components communicating with one another with asynchronous messages. Notably, conventional messaging systems have been used to build highly reliable, scalable, and flexible distributed applications.
At its core, the conventional messaging system permits separate, uncoupled applications to reliably communicate in an asynchronous manner. Importantly, the messaging system architecture generally replaces the client/server model with a peer-to-peer relationship between individual computing components, wherein each peer computing component can send and receive messages to and from other peer computing components. In consequence, messaging systems can provide several significant advantages over other, more conventional distributed computing models.
For instance, messaging systems encourage “loose coupling” between message consumers and message producers. Specifically, there exists a high degree of anonymity between producer and consumer. In fact, from the perspective of the message consumer, it does not matter who produced the message, where the producer resided in the computing network, and when the message had been produced. As a result, dynamic, reliable, and flexible systems can be assembled whereby entire ensembles of sub-applications can be modified without affecting the remaining portion of the system. In any event, conventional messaging systems assume one of two messaging systems models: publish/subscribe and point-to-point.
The publish/subscribe messaging system supports an event driven model where consumers and producers participate in the transmission of messages. Producers “publish” messages, while consumers “subscribe” to messages of interest, and consume the messages. More particularly, producers associate messages with a specific topic, and the messaging system routes messages to consumers based upon the topics for which consumers have registered. In point to point messaging systems, by comparison, messages are routed to an individual consumer which maintains a queue of “incoming” messages. Messaging applications send messages to a specified queue, and clients retrieve messages from a queue.
The Java™ Message Service (JMS), part of the Java 2 Enterprise Edition (J2EE™) suite manufactured by Sun Microsystems of Palo Alto, Calif., provides standard APIs that Java developers can use to access the common features of enterprise messaging systems. JMS supports both the publish/subscribe and point-to-point models and allows the creation of message types consisting of arbitrary Java objects. A fundamental design goal of JMS is to provide a consistent set of interfaces that messaging system clients can use independent of the underlying message system provider. In this way, not only are client applications portable across machine architectures and operating systems, but the client applications also remain portable across messaging products.
Still, in JMS only a single thread can be used to service a messaging system subscriber receiving any published message for a customer defined topic in which it is interested. In consequence, if enough message traffic is generated for that topic, a single thread in a multithreaded virtual machine can become overrun fairly quickly. Accordingly, what is needed is a messaging system in which multiple threads can service a messaging system subscriber receiving any published message for a customer defined topic.